Segfault when listing remote branches

**Describe the bug**

I tried to list the remote branches in one of my remotes and `lazygit` crashed with a panic. The stacktrace is below.

For context, I have 2 remotes, one points to a public repo in github.com, let's call it "oss"; the other remote points to an internal repo in GitHub Enterprise, let's call it "private".

The remote in "private" has to be updated from time to time from "oss" main branch. The default branch is tracking `main` in the "private" remote. My workflow consists on pulling the latest changes from "oss" main branch onto a local branch named `oss_main`, merge `oss_main` into `main`, then push `main` to "private". Since Lazygit already fetches the remotes, I checkout `oss_main`, visit the "remotes" tab, select the "oss" remote, find `main` and perform a regular merge (this saves some network since "pull" re-fetches the remote).

I got the segfault when I hit "enter" in the "remotes" tab, to list the remote branches. I don't remember if I tried to list the remote branches in "oss" or "private" 😔

stacktrace.out

```
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x10 pc=0x100767a54]

goroutine 1 [running]:
github.com/jesseduffield/lazygit/pkg/commands/models.(*RemoteBranch).FullName(...)
github.com/jesseduffield/lazygit/pkg/commands/models/remote_branch.go:10
github.com/jesseduffield/lazygit/pkg/gui/context.NewRemoteBranchesContext.func3.GetRemoteBranchListDisplayStrings.1(...)
github.com/jesseduffield/lazygit/pkg/gui/presentation/remote_branches.go:12
github.com/samber/lo.Map[...](...)
github.com/samber/lo@v1.31.0/slice.go:29
github.com/jesseduffield/lazygit/pkg/gui/presentation.GetRemoteBranchListDisplayStrings(...)
github.com/jesseduffield/lazygit/pkg/gui/presentation/remote_branches.go:11
github.com/jesseduffield/lazygit/pkg/gui/context.NewRemoteBranchesContext.func3(0x140000a2d40?, 0x10076fe6c?)
github.com/jesseduffield/lazygit/pkg/gui/context/remote_branches_context.go:32 +0xb4
github.com/jesseduffield/lazygit/pkg/gui/context.(*ListRenderer).renderLines(0x14000148a10, 0xffffffffffffffff, 0xffffffffffffffff)
github.com/jesseduffield/lazygit/pkg/gui/context/list_renderer.go:93 +0x160
github.com/jesseduffield/lazygit/pkg/gui/context.(*ListContextTrait).HandleRender(0x14000148a00)
github.com/jesseduffield/lazygit/pkg/gui/context/list_context_trait.go:110 +0x11c
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).postRefreshUpdate(0x14000162008, {0x100d71e98, 0x140000ae5d0})
github.com/jesseduffield/lazygit/pkg/gui/view_helpers.go:136 +0x84
github.com/jesseduffield/lazygit/pkg/gui.(*guiCommon).PostRefreshUpdate(0x1014d77d0?, {0x100d71e98?, 0x140000ae5d0?})
github.com/jesseduffield/lazygit/pkg/gui/gui_common.go:34 +0x28
github.com/jesseduffield/lazygit/pkg/gui/controllers.(*RemotesController).enter(0x140000ae9d8, 0x14000b5a080)
github.com/jesseduffield/lazygit/pkg/gui/controllers/remotes_controller.go:130 +0x1cc
github.com/jesseduffield/lazygit/pkg/gui/controllers.(*RemotesController).GetKeybindings.(*ListControllerTrait[...]).withItem.func1()
github.com/jesseduffield/lazygit/pkg/gui/controllers/list_controller_trait.go:116 +0x48
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).callKeybindingHandler(0x14000162008, 0x14001792aa0?)
github.com/jesseduffield/lazygit/pkg/gui/keybindings.go:540 +0x11c
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).SetKeybinding.func1()
github.com/jesseduffield/lazygit/pkg/gui/keybindings.go:485 +0x24
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).SetKeybinding.(*Gui).wrappedHandler.func3(0x14001cab3c8?, 0x1001b8f50?)
github.com/jesseduffield/lazygit/pkg/gui/keybindings.go:479 +0x24
github.com/jesseduffield/gocui.(*Gui).execKeybinding(0x1?, 0x0?, 0x14001cab428?)
github.com/jesseduffield/gocui@v0.3.1-0.20250522064656-07eb9218e08e/gui.go:1565 +0x6c
github.com/jesseduffield/gocui.(*Gui).execKeybindings(0x14000092a80, 0x140000f7448, 0x14001cab560)
github.com/jesseduffield/gocui@v0.3.1-0.20250522064656-07eb9218e08e/gui.go:1524 +0x3bc
github.com/jesseduffield/gocui.(*Gui).onKey(0x140002823e8?, 0x14001cab4e0?)
github.com/jesseduffield/gocui@v0.3.1-0.20250522064656-07eb9218e08e/gui.go:1331 +0x58
github.com/jesseduffield/gocui.(*Gui).handleEvent(0x140002823c0?, 0x14001cab548?)
github.com/jesseduffield/gocui@v0.3.1-0.20250522064656-07eb9218e08e/gui.go:848 +0x40
github.com/jesseduffield/gocui.(*Gui).processEvent(0x14000092a80)
github.com/jesseduffield/gocui@v0.3.1-0.20250522064656-07eb9218e08e/gui.go:802 +0x180
github.com/jesseduffield/gocui.(*Gui).MainLoop(0x14000092a80)
github.com/jesseduffield/gocui@v0.3.1-0.20250522064656-07eb9218e08e/gui.go:781 +0x108
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).Run(0x14000162008, {{0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}})
github.com/jesseduffield/lazygit/pkg/gui/gui.go:867 +0x434
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).RunAndHandleError.func1()
github.com/jesseduffield/lazygit/pkg/gui/gui.go:873 +0x48
github.com/jesseduffield/lazygit/pkg/utils.SafeWithError(0x14000045928?)
github.com/jesseduffield/lazygit/pkg/utils/utils.go:81 +0x5c
github.com/jesseduffield/lazygit/pkg/gui.(*Gui).RunAndHandleError(0x14000162008, {{0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}})
github.com/jesseduffield/lazygit/pkg/gui/gui.go:872 +0xc4
github.com/jesseduffield/lazygit/pkg/app.(*App).Run(...)
github.com/jesseduffield/lazygit/pkg/app/app.go:270
github.com/jesseduffield/lazygit/pkg/app.Run({0x100d6a878?, 0x140001be160?}, 0x14000189940, {{0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, {0x0, ...}})
github.com/jesseduffield/lazygit/pkg/app/app.go:48 +0xb0
github.com/jesseduffield/lazygit/pkg/app.Start(0x14000045ef8, {0x0, 0x0})
github.com/jesseduffield/lazygit/pkg/app/entry_point.go:168 +0x9b0
main.main()
github.com/jesseduffield/lazygit/main.go:23 +0x98
```

**To Reproduce**

I can't reproduce the issue 🙁 What I was doing when the crash happened:

1. Go to "remotes" tab
2. Press "enter" to list the remote branches
3. See error

**Expected behavior**
Lazygit does not crash, and lists the remote branches.

**Version info:**
_Run `lazygit --version` and paste the result here_

```
lazygit --version
commit=, build date=, build source=Homebrew, version=0.51.1, os=darwin, arch=arm64, git version=2.49.0
```

_Run `git --version` and paste the result here_

```
git --version
git version 2.49.0
```

**Additional context**

N/A

**Note:** please try updating to the latest version or [manually building](https://github.com/jesseduffield/lazygit/#manual) the latest `master` to see if the issue still occurs.